This PR fixes the bug found in issue #8108.

When the random() function was called like in the example below, it was incorrectly set to foldable, making the result a constant so both rows contained the same value. Now the BoundFunctionExpression::IsFoldable() function also checks the bound lambda expression for side effects, creating two different random values.

select [random() for _ in range(1)]  from range(2);